1. Field of the Present Invention
The present invention relates generally to seal structures to prevent the flow of fluid through gaps between a stationary element and movable element, and more particularly to a fluid seal for use in the high temperature environment of a turbine engine.
2. Description of the Prior Art
Conventional fluid seals, often used to prevent the leakage of gas between parts of a turbine engine, are constructed in a variety of shapes and sizes. For example, "O" rings are a well known form of seal used to close the gap between parts of a turbine engine. Other known forms of seals comprise labyrinth seals, feather seals, carbon rub seals, viscoseals, compression seals, step seals and packed glands. However, many such seals are primarily intended for use between stationary parts for the reason that relative movement between the parts causes wear and destruction of the seal. Worn seals can cause leakage of gas or other fluids, and therefore, would require repeated replacement in order to remain effective.
Moreover, the previously known seals have a fixed geometry and when used in high temperature environments or where the seals are subjected to pressure or temperature changes, they can deform from their initial shape. As a result, they are subject to the disadvantages of high leakage, the exertion of high frictional forces on mating parts which must move relative to one another, or, like labyrinth seals, are very complex and thus costly to produce and replace. Moreover, in high temperature environments, the sealing ability and the working life of these seals can be substantially adversely affected by the high temperature environment. Thus, while it may be useful to utilize highly specialized materials in constructing these seals, the production and composition of these previously known seals substantially increases the cost and complexity of such seals.